The present invention relates to a method, a device and a plant for cleaning irregular pieces of different materials.
It should be understood that in the context of the present specification with the terms xe2x80x9ccleaningxe2x80x9d or xe2x80x9ctreatingxe2x80x9d is meant a removing action for removing from material pieces an agglomerated material sticking or adhering thereon.
As it is known, for example, from pyrolysis processes, so called parallelepipedical xe2x80x9ccakesxe2x80x9d or blocks consisting of compressed coal dust incorporating in the upper side thereof cup-like elements of cast iron in which may be engaged teeth of a translation rod for moving said blocks. During the stay time of said blocks in the treating baths an irregular thin contaminating layer called in the art terminology xe2x80x9ccontaminating filmxe2x80x9d is formed onto the block outer surface.
Due to cost reasons it is desirable to recover or recuperate both a cleaned metallic fraction or component, that is the cast iron pieces from which the sticking coal parts have been removed, as well as a cleaned coal fraction or component, that is the coal pieces from which the sticking contaminating film parts have been removed.
The cleaning or recovering step is usually preceded by a preliminary breaking of said coal blocks and cast iron elements into smaller pieces. These obtained smaller cast iron pieces may have a granulometry at will.
Said breaking step can practically occur in different ways and providesxe2x80x94as mentioned abovexe2x80x94a component of cast iron pieces having coal dust agglomerations sticking thereon and a component of compressed coal dust pieces bearing portions of said contaminating film thereon, the volume ratio between said components being, for example, of about 1 to 20.
The cleaning treatment of both the component of cast iron pieces and the component of coal pieces, are carried out with rather empirical methods, for example by tumbling for the cast iron pieces or by a manual scrapping or by abrasion by means of a sand jet for both the metal and coal pieces. These methods require a long treatment/cleaning time indeed, are noisy, cause the formation and emission of a great quantity of contaminating volatile coal dust, and have a low efficiency due to both the weak separation/removing action, particularly in the case of said cast iron pieces, and the difficulties to remove in a reliable and complete way said contaminating film from the coal pieces.
Due to the different features and hardness of the cast iron and coal pieces it is further known to utilize two separated, independent and rather long tumbling barrel-like devices, and more precisely: one for treatment/cleaning the metallic component, and another for removing said contaminating film from the coal pieces. This obviously requires a considerable expenditure in investments, equipment, personnel, and installation surface.
The presence of volatile coal dust, particularly of the contaminating coal dust, is harmful for the operators, causes pollution, and requires a costly plant for eliminating the coal dust.
Although in the present specification reference is made to said above mentioned xe2x80x9ccakesxe2x80x9d or blocks for pyrolysis processes, the teaching of the present invention refers without limitations to the cleaning of any other product requiring a similar cleaning/removing operation.
The main object of the present invention is to provide a method, a device and a plant able to eliminate the drawbacks and shortcomings of the prior art and to allow a reuse of both components of different materials, for example cleaned cast iron pieces and compressed coal dust pieces, by using of only one cleaning device or plant.
Another object of the present invention is to achieve both a high cleaning degree of the cast iron pieces and a high cleaning efficiency of the coal piece cleaning step, as well as to eliminate the coal dust emission in the work environment.
Still another object of the present invention is to separately collect the reusable fine coal dust removed from the cast iron pieces and the contaminating film to discard fine coal fraction from the coal pieces.
These and other objects are achieved with a method, a device and a plant for cleaning irregular pieces of different materials which present the features recited in the independent claims.
Further developments and advantageous embodiments of the present invention are set forth in the dependent claims.
With the method, device and plant according to the present invention it is possible to achieve several advantages.
First of all, the efficient, desired and different cleaning actions carried out, for example, onto the pieces of the metallic component and the coal component obtained from the starting coal xe2x80x9ccakesxe2x80x9d or blocks for pyrolysis processes as a function of only the direction of rotation of a single cleaning device allow to utilize only one treatment/cleaning device.
Furthermore, the desired cleaning degree may reliably be achieved with a continuous operation independently of the cleaning device length by a sequence of cleaning cycles.
Still another advantage is to obtain an optimum cleaning degree of both the harder cast iron pieces and the softer coal pieces in a considerably shorter time with reference to the prior art.
Furthermore, the treatment/cleaning time as well as the number of cleaning cycles can advantageously be easily decided either by an operator based on a visual checking or automatically based on an optic checking by an optic detector and cleaning reference values obtained in practice.
The achieving of both said different cleaning actions in the same treating/cleaning device obviously allows a remarkable reduction of the expenditure for apparatuses and control/adjusting circuits and requires only a small installation surface.
The used apparatuses and conveying tapes can be easily and cheaply cladded so that noises are reduced and the harmful coal dust emissions are eliminated, which also allows an installation of the cleaning device and plant under a covering, that is, for example, in a shed or the like.
A changing-over from the cleaning step for cast iron pieces to that for coal pieces may take place instantaneously and does not require any preliminary conversion of the cleaning device or a tool substitution.
Another advantage is to be seen in the fact that the collecting of the fine coal fractions may take place automatically both during the piece feeding step and the cleaning step of the pieces to be cleaned and, therefore, separated recovering or collecting steps are not necessary.
With the feature of claim 2 can be obtained a quick and efficient removing of the coal parts sticking onto the cast iron pieces and a discharging of the removed coal parts which latter during the cleaning step are automatically crushed with a fine granulometry.
A surprisingly simply, efficient and total removal of the contaminating film can be achieved with the teaching of claim 3 which is based on the fact that the inventor has established that said contaminating film has a lower mechanical resistance and consistency and is more crumbly than the coal pieces consisting of compressed coal dust.
The features set forth in claim 4 allow to adjust the productivity of the cleaning device or plant when cleaning both the metal and coal components in a simple way and with usual components of the adjusting technique.
With the feature of claim 6 has been achieved in practice an efficient and continuous elimination of the coal fine fraction in the cleaning device during the cleaning step itself.
Simple embodiments of the cleaning tools can be constructed with the teaching of claim 7 which further suggests another measure for avoiding possible distortions of the free edge of said cleaning tools which distortions could hinder a free sliding and a following free fall by gravity of the pieces onto the lifted tools and is illustrated in FIG. 9.
The configuration of the treatment/cleaning tools set forth in claim 8 guarantees a high cleaning efficiency of both the metal and the coal components.
The cleaning tools suggested in claim 9 can be constructed in a simple and inexpensive manner and can be easily fastened to the cleaning jacket, for example by welding or screwing.
The embodiment of the tools according to claim 10 can be constructed in a very simple, quick and inexpensive way and ensures a high cleaning efficiency.
With the cleaning tools disclosed in claim 11 it is possible to obtainxe2x80x94with straight toolsxe2x80x94an easy adjustment of the productivity by varying down from above the output end of the cleaning jacket, andxe2x80x94with helicoidal toolsxe2x80x94to obtain an automatic discharging of the cleaned material without any tilting of said cleaning jacket, the productivity adjusting being easily obtained by varying the rotation speed of said cleaning jacket.
A good balancing of the cleaning jacket during the rotation thereof may be achieved with the teaching of claim 12.
Claim 14 teaches an embodiment of a feeder-separator for feeding the materials to be cleaned which is easy to construct, simple to adjust and has a reliable operation.
A simple construction for conveying the fine coal fractions on a discharging belt is suggested in claim 15.
The conveying path disclosed in claim 16 can be carried out with a development at will which may be further easily adapted to the planimetry of the respectively considered installation area and can be further composed with usual components.
The feature stated in claim 17 allows to automate the entire cleaning cycle/operation by using usual components of the analogical and digital techniques, an appropriate control program co-operating with a microprocessor as well as stored reference cleaning degree values previously determined in practice.
With the feature set forth in claim 18 it is possible to comply with the noise limits prescribed by the specifications for installations in sheds as well as to avoid an harmful emission of coal dust in the working environment during the cleaning operation.
The teaching of claim 19 allows to automatically carry out the operation of the plant according to the present invention even in the case of a plant installed inside a shed and closed by a cladding or case.
The measure set forth in claim 19 aims to obtain cleaning tools having a long life and easy to restore by substituting a removable part thereof, for example a liner consisting of hardened metal.